1. Field of the Invention
The present invention relates generally to electrostatic or ionic air purifiers and, more specifically, to an ionic air purifier having a high air flow volume and clean air delivery rate (CADR).
2. Description of the Related Art
An ionic air purifier typically includes a louvered or grilled housing in which an ionizer unit electrostatically attracts and removes particulate matter from the air. The ionizer unit includes two spaced-apart arrays of electrodes coupled to the respective positive and negative high voltage output ports of a power supply. The electrodes of one array, which are sometimes referred to in the art as a corona electrodes, are typically thin and wire-like, and electrodes of the other array, which are sometimes referred to as collector electrodes, are typically blade-shaped. The voltage between the electrodes is typically on the order of 10-20 kilovolts.
Ionic air purifiers typically utilize electro-kinetic principles to produce air flow without the use of fans or other mechanically moving parts. The electric field that is generated between the first and second electrode arrays produces an electro-kinetic airflow moving from the first array toward the second array. Ambient air, including dust particles and other undesired particulate matter, enters the housing through the grill or louver openings on the upstream side of the housing, is charged by the corona electrode array, and particulate matter entrained in the air is electrostatically attracted to the surface of the collector electrode array, where it remains, thus removing particulate matter from the flow of air exiting the housing through the grill or louver openings on the downstream side of the housing. The collector electrode array can be cleaned of trapped particulate matter by removing the assembly from the housing and wiping the blades with a cloth.
The high voltage electric field present between electrode arrays can cause a corona effect that generates ozone (O3) and nitrogen oxides (NOx). Ozone inhibits the growth of bacteria, molds and viruses and helps eliminate odors in the output air, but as high concentrations of ozone are harmful to human health, it is desirable to control the release of ozone.
Low air flow velocity and concomitant low air flow volume, i.e., the amount of air that moves through the purifier in a given amount of time, are problems with conventional ionic air purifiers of the type described above. While it is known that increasing the power drawn by the electrode arrays will increase the electro-kinetic airflow, it can also increase generation of undesirable amounts of ozone and nitrogen oxides.
It would therefore be desirable to provide an ionic air purifier that maximizes air flow volume yet controls generation of ozone and other corona effect products. The present invention addresses these problems and deficiencies and others in the manner described below.